Loading & using equations

:confused: I'm a beginner programmer stuck on how to implement this function for my program, any suggestions will be very welcome (save my hair).

I want the user to input a mathematical equation e.g. y=m*x+c (using Visual C++).

My problem is to then find a way that this can be a) used by the program, b) saved to file, c) opened and used from the saved file.

As you can see this has me pretty much stumped......what variable type do i use that will recognise the mathematical symbols? Do i pass the input equation as a string vaiable and then write coding to pull out all mathematical symbols.......like pulling teeth :(

Help basically.

Thanks.